Fabrication, characterization, and optimization of the composite long afterglow material Sr2MgSi2O7:Eu2+, Dy3+@ SrAl2O4:Eu2+, Dy3+

In order to improve the water resistance of SrAl 2 O 4 :Eu 2+ , Dy 3+ , the composite long afterglow material Sr 2 MgSi 2 O 7 :Eu 2+ , Dy 3+ @ SrAl 2 O 4 :Eu 2+ , Dy 3+ was prepared by covering uniform and stable Sr 2 MgSi 2 O 7 sol on SrAl 2 O 4 :Eu 2+ , Dy 3+ powder, which was synthesized via traditional solid-state method. The effects of various factors, such as the amount of ammonia, the molar ratio of Sr 2 MgSi 2 O 7 :SrAl 2 O 4 and the content of H 3 BO 3 , on the structure and luminescent properties of Sr 2 MgSi 2 O 7 :Eu 2+ , Dy 3+ @ SrAl 2 O 4 :Eu 2+ , Dy 3+ were investigated by the response surface method. The results show that the influence extent on both the initial afterglow brightness and water resistance are as follows:the amount of ammonia> the content of H 3 BO 3  > the molar ratio of Sr 2 MgSi 2 O 7 :SrAl 2 O 4 . When the amount of ammonia, the molar ratio of Sr 2 MgSi 2 O 7 :SrAl 2 O 4 and the content of H 3 BO 3 is 1.64 mL, 11.10, and 0.006 mol, respectively, both the brightness and water resistance of Sr 2 MgSi 2 O 7 :Eu 2+ , Dy 3+ @ SrAl 2 O 4 :Eu 2+ , Dy 3+ are improved, the water resistance is 0.835 (51.82% higher than that of pure SrAl 2 O 4 ) and the initial afterglow brightness can reach 2793 mcd/m 2 (91.69% higher than that of pure SrAl 2 O 4 ), which were in good agreement with the predicted optimum value of 0.867 and 2720 mcd/m 2 , respectively. Under the optimization conditions, the synergistic action of SrAl 2 O 4 with excellent afterglow properties and Sr 2 MgSi 2 O 7 with high water resistance plays an important role in improving the water resistance without sacrificing brightness. Finally, the water-based light-emitting inks with SMSA as fluorescent pigment exhibit excellent luminescent properties in the dark. Graphical abstract